MUTATION IN MATTHIOLA ANNUA, A "MENDELIZINC 
SPECIES! 
Howard B. Frost 
Interest in the subject of mutation seems to be growing, and with 
good reason. Varied as may be the processes concerned in the pro- 
duction of mutant forms, evidence is accumulating to show that some- 
times, at least, mutation involves fundamental chemical or structural 
changes in the germ-plasm. It is obviously of great importance in 
practical breeding, and we cannot yet safely deny to it a significant 
role in evolution. 
In view of the peculiarities in the general genetic behavior of 
Oenothera, it has become a matter of special importance to study 
mutation in plant forms that are known to exhibit typical Mendelian 
phenomena. Two general views of heredity in Oenothera appear 
still to be possible; first, the one recently expressed by Shull (1913), 
that regular segregation and recombination of genetic factors are ab- 
sent; second, that the irregularity is secondary, and due to compli- 
cating influences, especially to selective sterility. Perhaps the 
genus possesses peculiarities of chromosome structure and behavior 
which will be found to justify a view practically intermediate between 
the two just stated. 
It now seems very probable, whatever the fundamental reason, 
that other genera are to be classed with Oenothera as possessing certain 
genetic peculiarities. In Citrus, for instance, we find a similar tend- 
ency toward apparent mutation, which is very strikingly manifested 
by somatic tissues. Here, also, sterility seems to be common, as with 
the Washington navel orange, where it is complete in the anthers, and 
with the Satsuma mandarin, where very few of the pollen-grains are 
capable of germination. Probably the potato (or the genus Solanum ?) , 
with its apparent somatic mutation, its doubtfully regular genetic 
ratios, and its very general pollen-sterility, also belongs to this group. 
If Oenothera is thus typical of a group of genera, we may expect to 
1 Paper No. 27, Citrus Experiment Station, College of Agriculture, University 
of California, Riverside, California. 
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